The largest spider found anywhere in Wisconsin — capable of reaching three inches in size — seems to be turning up in this part of the state in growing numbers.

Known as a "fishing spider," it has been spotted this year in Door County, Oconto County, Marinette County and Fond du Lac County.

Although it is not harmful to humans, the eight-legged creature is known for being large enough and aggressive enough to go underwater and hunt down small fish or other aquatic life.

A fishing spider can be seen in the upper right corner on top of this birdhouse in Vilas County.(Photo: Submitted)

It also has the ability to scare the heck out of anyone who is afraid of spiders.

"It's going to freak them out," said Linda Williams of the Wisconsin Department of Natural Resources. "It is pretty impressive."

Williams, a forest health specialist based in Green Bay, said that while two or three fishing spider sightings annually are typical in the region, she has received 10 reports this year and has personally seen another four spiders herself.

The DNR this week took to social media with an alert about fishing spiders and pictures of one found clinging to a birdhouse in Vilas County.

The spiders are commonly found around rivers, streams or lakes, but they also will frequently drift into backyards or elsewhere to find food or lay eggs. In urban settings, they are not uncommon around bridges or along rocky riverbanks.

"You could pretty much find them anywhere in Wisconsin," said Michael Draney, a spider expert and science professor at the University of Wisconsin-Green Bay.

Draney said he, too, has noticed an increase in sightings, especially of the "dark fishing spider," which is one of six variations. The fishing spider is native to Wisconsin and can be found throughout the Midwest.

Since the spiders live up to three years, it is difficult to tell when or why a population boom might have occurred in Northeastern Wisconsin, Draney said. But anyone who comes across one of these creatures — which can grow to about half the size of a tarantula — is not likely to forget it any time soon.

On a camping trip this summer to an island north of Door County, Draney said he spotted several of the spiders. He also has heard more people talking about their own encounters.

"It definitely makes an impression," he said.

Fishing spiders, which are native to Wisconsin, can live up to three years and grow to be three inches in size.(Photo: Submitted)

In addition to being unusually large, the fishing spider is able to move quickly on either land or water. It can race along the surface of water or dive beneath to hunt for food.

If small fish or tadpoles are not available, the spider will feed on other small insects.

Although not aggressive toward humans, the spider can inflict a bite similar to a mosquito bite, most likely if someone decides to touch or grab the spider.

Blegen, a retired high school biology teacher near Spring Valley, has seen many fishing spiders around his home. One of them has made a home in a wood pile for the past couple of years.

Blegen questions whether fishing spiders are becoming more abundant, or whether sightings are just becoming more common. Either way, he said, the experience for each person almost certainly is a memorable one, especially for anyone who is not fond of spiders.

He added: "It'll make a very hairy memory."

— swilliams@pressgazettemedia.com and follow him on Twitter @pgscottwilliams.